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Electromechanical force transducer

a technology of force transducer and force transducer, which is applied in the direction of electromechanical transducer, transducer diaphragm, instruments, etc., can solve the problems of poor damping performance and achieve the effect of improving the robustness of the transducer and reducing the chance of failur

Active Publication Date: 2009-01-13
GOOGLE LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The invention is about a new type of transducer that can improve the damping performance of resonant elements. By using a flexible reference layer with high resistance to dimensional change, the damping layer can now shear between the changing element face dimension and the non-stretching foil, resulting in an improvement in damping. This is achieved by adhering the damping layer between adjacent element faces. Additionally, the invention introduces out of plane DMA modes into the audio band and provides a bending inertial vibration transducer with improved rotational impedance.

Problems solved by technology

We have found that simply adding a damping layer to one face of a resonant element or beam gives poor damping performance as the layer stretches with the element as the element face changes dimensions.

Method used

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  • Electromechanical force transducer
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Examples

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Embodiment Construction

[0030]FIG. 1 shows a double beam transducer of the kind generally described in WO01 / 54450, the text of which is incorporated in the present application. The transducer (1) comprises a first piezoelectric beam (2) on the back of which is mounted a second piezoelectric beam (3) by connecting means in the form of a rigid stub (4) located near to the centre of both beams. Each beam is a bimorph.

[0031]The transducer (1) is mounted on a structure (5), e.g. a bending-wave loudspeaker panel, e.g. a distributed mode loudspeaker (DML), by coupling means in the form of a rigid stub (6) located near to the centre of the first beam.

[0032]In the present invention a low stiffness layer (7) of foamed plastics is bonded between adjacent faces of the two beams (2,3). The bonded layer may cover substantially the whole of the adjacent faces or may be discontinuous, e.g. to damp certain modes.

[0033]The following sets out some parameters for one suitable foam damping material.

[0034]“Poron” slow rebound f...

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PUM

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Abstract

An electromechanical force transducer comprises at least two adjacent resonant elements and a damping layer coupled between their adjacent faces. The damping layer is selected so that the output is increased in the region of internal cancellation in the transducer. The adjacent resonant elements are beam-like and have substantially the same length. The resonant elements may be supported on a stub of low rotational stiffness whereby the fundamental resonance of the transducer becomes less dependent on bending motion of the transducer and more rigid body-like. The transducer may also include a member for increasing the rotational impedance of the transducer.

Description

[0001]This application is a continuation-in-part of International patent application No. PCT / GB2004 / 003843, filed Sep. 9, 2004, which is incorporated herein by reference in its entirety.TECHNICAL FIELD[0002]The invention relates to electromechanical force transducers, actuators, exciters and the like devices and more particularly but not exclusively, to such devices for use in acoustic apparatus, e.g. loudspeakers and microphones.BACKGROUND[0003]The invention relates particularly, but not exclusively, to electromechanical force transducers of the kind described in International patent application WO01 / 54450 to the present applicant (incorporated herein by reference), and comprising one or more resonant elements or beams having a frequency distribution of modes in the operative frequency range of the transducer. Such transducers are known as “distributed mode actuators” or DMA for short.[0004]It is an object of the invention to provide a transducer in which damping is provided to res...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): G01B7/16
CPCG01L1/10H04R7/00H04R17/00H04R7/045
Inventor STARNES, MARK WILLIAMEAST, JAMES JOHNOWEN, NEIL SIMONHOYLE, STEVEN MARK
Owner GOOGLE LLC